That the Messenger of Allah (ﷺ) used to say the taslim to his right and to his left.
Sunan an-Nasa'i Book 13, Hadith 138
← Previous Hadith "I said: 'O Mother of the believers! Tell me about the Witr of the Messenger of Allah (ﷺ).' She said: 'We used to prepare his siwak and water for purification, then Allah (SWT) would wake him when He willed to wake him at night. He would use the siwak and perform wudu, then pray eith rak'ahs; not sitting until the eighth rak'ah, when he would sit and remember Allah (SWT) and call upon Him. Then he would say the taslim loud enough for us to hear.'"

Sunan an-Nasa'i Book 13, Hadith 137 Next Hadith → "I used to see the Messenger of Allah (ﷺ) saying the taslim to his right and to his left until the whiteness of his cheek could be seen."

Sunan an-Nasa'i Book 13, Hadith 139